So let's talk about those drugs that directly act on the receptors. Let's cover the blockers of those receptors first. So alpha blockers are nonselective and selective. The nonselective alpha blockers are Phenoxybenzamine and Phentolamine. I want you to remember this drugs. I'm only going to pick the ones that you are going to be tested on. There are literally hundreds within each class. So let's just focus on the important ones but you do need to know them. The alpha 1 selective agent of choice is Prazosin and the alpha 2 selective agent is Yohimbine. I have never used Yohimbine in clinical practice but I always remember it because it's the one that we had to memorise for exams. Let's talk about beta blockers now. The nonselective prototypical beta blocker is Propanolol. Beta 1 selective agent, the example that we always use is Atenolol which is kind of an older beta blocker and replaced by newer ones. But it's the prototypical one that I want you to remember. Beta 2 selective beta blockers is Butoxamine which is almost never used clinically but it's important for research. And it is the prototypical drug so you do need to know it. Beta blockers that start with the letters A-M are generally those drugs that tend to be beta 1 selective and useful for cardiac inhibition. Acebutolol, atenolol, bisoprolol, esmolol, labetolol, metoprolol. Those are the commonly used clinical ones. But if you remember A-M is beta 1 selective and for the heart you'll be a long way. The beta blockers that start with C, C stands for cardiac. And these are the drugs we tend to use in cardiac failure. So the prototypical drug of the heart failure beta blockers is carvedilol. And the reason why carvedilol is so unique is because...